Hardening furnace with continuously operating charging device



Sept. 1, 1931. E. GOERIG :TAL A 1,821,832.

HARDENING FURNACE WITH CONTINUOUSLY OPERATING CHARGING DEVICE FiledMarch 28, 1929 Patented sept. 1, 1931v ERNST. Gonnie, or MANNnnIlvLANnHummel-r, nINnHoi-tsr, orYBnRLIN, GERMANY y HARDENING summon warnGenerique-.Usar ernnamrne' cnnnema nnvrcnA Application med March ze,192e, serial No. strives,` and in Germany December 1e, 192s.

The present invention relates toV a hardening furnace, which isespecially suited for the hardening of large quantities of products andin which acementing` powder is used of which only relatively smallamounts are introduced into the furnace. The essential part of thispowder will gasify and the developed hot gases under Vpressure'willeifect the hardening action.

In such furnaces it is'` advantageous to add Vthe cementing powderslowly and by degrees into the hardening space so that the hardening gasis developed gradually, and in most cases it is necessary to replenishthe cementing powder in the lfurnace several times `during the hardeningprocess. The slow addition of the powder must occur without opening thedrum, because it is ofV utmost importance that the hot gas under itselevated pres-L sure does not escape, and that the pressure ortemperature of the same is not lowered. It is further necessary thatthe'powder charging device* operate accurately,rso that 'the yamountofpowder necessary for the treatment of a. furnace charge is added tothe furnace in portions of exactly the same weight and at regular timeintervals. Above all great care must be taken to prevent the powderfeeding'device'from becoming clogged. The cementing powder isfrequent-lv moist vand during the I.Q'asiiication steam isf oftenformed, which penetrates into the powder storing tank. wherebv thepercentage of moisture in the same is increased. Thereby the powder inthe tank will be converted into a cloddv mass, which will block up thetank and the discharge conduit therefor.

According to the present invention the above mentioned drawbacks areeliminated by means of a powder tank of specialform which cooperateswithy suitable feeding devices.

The invention is shown bv way of example in the accompanying `drawingsin which Fig. l is a sectional view of a preferred embodiment oftheinvention. p c

Figs. 2 and 3 show details of two modifications'of the scraper. Y

I According to Fig. l the greater part of the feeding tube 2v for thecementing agent Vof its own weight.

is arranged inside of the hardening drum l, which isheated in-knownmanner.` In the tube 2 and rigidly connected to the samea screw conveyor3 is located, which loosely -surrounds the pyrometer tube 4, so that thetube 2 and the conveyor?) may be rotated relatively to the pyrometertube 4. This tube is fastened in the tlange-like body 5, preferably lbymeans such as welding. Opposite to the body 5 a bearingv22lisarranged,which supports one end of the tube 2 and in which the tube maybe rotatedby means such as the worm wheel 6. The icernenting powder is stored in acontainer 8, and jis delivered to 1 the vconveyor 'through a; channel 9.The

velocity of rotation of the conveyor can be controlled and adjusted byymeans' of arrangements known per se and in this way the amountofvrpowder, which is fed at Vany timev of the feeding device mayaccording tothe Y invention be prevented by means of the sim pleandeicient device described below. l

Y Thepowd er tanks hitherto used were usually hopper-shaped. AccordimgVto thel present p invention the powder container consists of avertically arranged truncated ,cone of upwardly decreasing width, sothat the walls of vthe containerwill offer no'resistance to the powderwhich is dropping downward because lIn order to vfacilitate theemptying'of the container the bottom of the same is inclined towards theoutlet channel 9 which forms a direct continuation of the said bottom.This arrangement will be suiicient to prevent a baking of the powder,providedr that the same is in a relatively dry state.

t The disintegration Vof the cementing powder eifected by giving thecontainer a special shape. in order to prevent the outlet conduit .beingblocked, may be further. increased b v preheatinn the powder. o In thiscase the heating gases from the fire chamber of the furnace may beutilized. they being passed through a heating coil l0 arranged in thecontainer 8. Other heating fluids may be passed through the heatingcoil, for instance het water or the like.

Instead of the above described heating device or together with the sainethe following arrangement may be employed:

A shaft 15 is vertically arranged in the powder container and rotates inthe bearings 11. The shaft 15 is operated from the saine drivingarrangement as the worm wheel 6 or directly from this wheel. Alsoanother source of driving force may be employed and in this case theshaft may be rotated from the driving gear 12 by means of the shaft 13and the bevel gears 14. The gears 14 are surrounded by a protectivecover 19. At the lower end of the shaft 15 a scraper 16 is fastenedwhich rotates together with the shaft and feeds the powder through lthechannel 9 tothe conveyor 3. As shown in Fig. 2 the scraper or propeller16 is bent horizontally in such manner that the points of the sameproject in the direction of rotation, so that the powder caught by thepropeller will be forcedtowards the middle part of the scraper, that`is, towards the conduit 9. The wings of the scraper are further bentvertically in such manner that the front edge a when seen in thedirection of rotation assumes a raised position, whereas the rear edge bis lowered. The propeller 16 will therefore notonly guide the powdertowardsthe channel 9, but also press it into the saine, whereby thechannel cannot be blocked. The scraper may also consist of two differentcoacting elements and a device of the-kind is shown in Fig. 3. Accordingto this figure a member 20 is employed having the forni of a double wingthe points of which are bent forward `in the direction of rotation. Thismembery cooperates with a propeller 21, the wings of which may herelatively short, because the purpose ofthe saine is merely to press thecementing powder through the channel 9. The scraper arranged directlyabove the channel 9 and the middle par-t of 'the saine widened, partlybecause the stress isv greatest in this part and partly in order tocover the channel 9 see also Fig. 2) to prevent the powder dropping downinto the saine when the machine is at rest. Through this arrangement aspecial closing' device for .the channel 9 is made superfluous.' Y

In case the powder should be very moist ,a cross rod, or two oppositelylocated cross rods 17 may be arranged above the scraper or may heemployed. in its stead. These rods `are fastened to the shaft 15 and maybe equipped with vertically arranged pins 18, whereby double ralres areformed. Through `this device the` powder will be thoroughly rstirred andthe'balring of the same will be prevented. The device of Fig. 3 differssomewhat from that of Fig. 2, in that two plates `20 and 21 areprovided, arranged approximately 90o apart on the central shaft 15. Theplate 21 of the device of Fig. 3 is shown as having rearward ortrailing, convex surfaces b, and front or leading concave surfaces a.

We claim:

1. In a hardening furnace with continuously operating charging device, acontainer for cementing powder having a vertical axis and having theforni of a truncated cone, the cross-section of which decreases inupward direction, the container also converging slightly at its bottom,a device for conveying the cementing powder into the furnace, and acomparatively narrow channel connecting the said container with the saidconveying dev-ice.

2. In a hardening furnace with continuously operating charging device, acontainer for cenienting powder having a vertical axis and having theforni of a truncated cone, the

cross-section of which decreases in .upward direction, a device forconveying the cementing powder into the furnace, a comparatively `narrowchannel opening into the said con- .tainer and connecting the same withthe conveyor device and a bot-tom inthe container inclining towards theentrance tothe said channel.

3. In a hardening furnace with continu-- ously operating chargingdevice, a container for cementing powder having avertical axis andhaving the form of a truncated cone, the cross-section of whichdecreases in upward direction, a device for conveying the cementing.powder inte the furnace, a channel opening into the said container andconnecting the saine with the conveyor device, a bottom in the containerinclining downwardly towards the entrance t-o the said channel and' aheating device arranged on the inside of the said container.

4. In a hardening furnace with continuously operating charging device, acontainer for ceinenting powder having a vertical axis and having theform of a truncated cone, the cross-section of which decreases in upwarddirection.` a device for conveying the cementing powder into thefurnace, comprising a tube of uniform diameter and a screw conveyorwhich is Vrigidly connected to the inner surface of said tube, a channelopening into the said container and connecting the "saine with theconveyor device, a bottom in the container inclining downwardly towardsthe entrance to the said channel and means for moving the powder towardsthe said channel entrance.

5. In a hardening furnace with continuously operating charging device, acontainer' for cementing powder having a vertical axis and having theform of a truncated cone, the cross-section of which decreases in upwarddirection. a device for conveying the cementing powder into vthefurnace, comprising a i Il;

tube of uniform diameter and a screw conveyor which is rigidly connectedto the inner surface of said tube, a channel opening into the saidcontainer and connectingthe same with the conveyor device, a bottom inthe container inclining downwardly towards the entrance to the saidchannel and means for moving the powder towards the said channelentrance and for forcing it through the said channel. Y

6. In a hardening furnacerwith continuously operating charging device, acontainer for ccmenting powder having a vertical axis and having theforni of a truncated cone, the cross-section of which decreases inupward direction, a device for conveying the cementing powder into thefurnace, comprising a tube of uniform diameter and a'screw con# veyorwhich is rigidly connected to the inner surface of said tube, a channelopening into the said container and connecting the same with theconveyor device, a bottom in the container inclining downwardly towardsthe entrance to the said channel, a scraper arranged adjacent `the saidchannel entrance, the wings of said scraper being bent forward in thedirection of rotation of the same at their outer ends and having raisedfront edges and means for rotating said scraper.

7. In a hardening furnace with continuously operating charging device, acontainer for cementing powder having a vertical axisk and having theform of a truncated cone, the cross-section of which decreased in upwarddirection` a device for conveying the cementing powder into the furnace,comprising a tube of uniform diameter and a screw conveyor which isrigidly connected to the inner surface of said tube, a channel openinginto the said container and connecting the same with the conveyordevice, a bottom in the container inclining downwardly towards theentrance to the said channel, a scraper arranged adjacent the saidchannel entrance, a member having the form of a double hook. the outerparts of which project in the direction of rotation of the same, saidmember being arranged adjacent the said scraper and means for rotatingthe said scraper and the said member.

8. In a hardening furnace with continuously operating charging device, acontainer for cementing powder having a vertical axis and having theform of a truncated cone,v

the cross-section of which decreases in upward direction, a device forconveying the cementing powder into the furnace, comprising a tube ofuniform diameter and a screw conveyor which is rigidly connected to theinner surface of said tube, a channel opening into the said containerand connecting the same with the conveyor device, a bottom in Y thecontainer inclining downwardly towards the entrance to the said channel,rotatable members with wings adapted to move the powder towards the saidchannel entrance and to force it through the same, a widened part on thesaid rotatable members substantially covering the said lchannelentranceand means'for rotating said members.

9. In a hardening furnace with continuously operating charging device, acontainer for cementing powder having a vertical axis and having theform of a truncated cone, the cross-section of which decreases in upwarddirection, a device for conveying the cementing powder into the furnace,comprising a Vchannel entrance and to force it through the same, meansfor rotating/the said shaft and stirring mea-ns projecting from the saidshaft and adapted to stir the contents of the same thoroughly during therotation of the shaft.

In testimony whereof we aliix our signatures.

ERNST GOERIG. HEINRICH LINDHORST.

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